These colors are great, but almost ultraviolet to my eyes. I can only look at the map for 5 seconds. Also, the color doesn't really tell me how far from 50/50 the states are.
Here is some notes:
If anything, I'd say that the counties themselves are more divided than I thought. The one which surprises me the most is the deep south of texas, which is quite blue.
Also, I do not claim that I did this flawlessly, there is a chance I stuffed up and it is not showing the right data, but I don't really have the time to play with it for too long :)
I think this just highlights what people have been saying for quite a while now, that the political divide in this country isn't red states versus blue states, but urban versus rural. If you go to a level that separates those, as per-county does but per-state doesn't, you see a much bigger divide.
The most hotly contested states have (generally dense urban) blue city enclaves balancing against (generally sparse rural) red counties